This invention relates to tactile or touch sensor systems and methods particularly, although not exclusively, adapted for use with robotic devices and the like.
Robotics is rapidly becoming a major industry, and robotic devices are being used increasingly for such diverse purposes as manufacturing, assembly, metal forming and inspection, as well as in remote or hazardous environments. Although present generation robots are primarily preprogrammed to perform very specific tasks, major research efforts are underway to develop intelligent robots which are capable of reacting to changing environments and circumstances, and capable of imitating, to some extent, human functions and operations. This necessitates that a robot be capable of sensing its environment, and tactile or touch sensing is an important requirement for such purposes.
Early approaches to tactile sensing employed microswitches or binary pressure sensitive pads which provided little more than contact information. More recent approaches have employed proportional sensing elements typically arranged in an array or strategically located on the surface of a gripper to enable recognition of an object's shape and orientation. For the most part, tactile sensors are still primarily pressure sensitive or proximity sensitive devices, and known tactile sensors have a number of disadvantages.
It is recognized that a principal need for the next generation of robots is improved tactile sensing capable of providing continuously variable touch sensing over an area within which there is spatial resolution. Tactile sensor development in the past has been directed largely to improving transduction techniques and to increasing the spatial density of sensing arrays. The most commonly used transducer materials are conductive elastomeric, piezoresistive, or piezoelectric materials. Conductive elastomers have problems with nonlinearity, fatigue and nonrepeatability. Piezoresistive elements, although sensitive, linear and reliable, have a high per unit cost and poor spatial distribution limitations. Flexible piezoelectric polymers have attractive touch sensing possibilities and the advantages of being rugged, lightweight, and having good linearity and hysteresis characteristics, but their principal drawback is a lack of a DC response, thus necessitating the use of special signal capture techniques. Improving spatial density of sensor arrays requires smaller sensors, and there have been some efforts to develop smaller sensors.
It is desirable to provide improved touch sensor systems and methods which avoid these and other disadvantages of known systems and methods, and it is to this end that the present invention is directed.